ORCID Profile
0000-0002-2453-1485
Current Organisations
Massey University
,
Universiti Putra Malaysia
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Publisher: Elsevier BV
Date: 03-2016
DOI: 10.1016/J.VETPAR.2016.01.003
Abstract: Although only recently recognised, Theileria orientalis (Ikeda) is now the most important infectious cause of anaemia in New Zealand cattle. The aim of this study was to test if vertical transmission of T. orientalis (Ikeda) from dam to calf across the placenta occurs in naturally infected New Zealand dairy cattle and to also test whether the infection status of the dam at calving affects the future susceptibility of its offspring to T. orientalis (Ikeda) infection. Dairy cows (n=97) and their calves were s led at calving and the calves again at 4 months of age. All s les were measured for haematocrit and screened for T. orientalis genotypes using a multiplex Buffeli, Chitose and Ikeda specific TaqMan assay. Ikeda positive s les were further tested by singleplex PCR in triplicate to calculate the Ikeda infection intensity as genomes/μl of blood from each infected animal. No T. orientalis (Ikeda) infected calves were born to either T. orientalis (Ikeda) infected or uninfected dams. There were 56/97 dams positive for T. orientalis (Ikeda) infection at calving and 79/90 calves positive for T. orientalis (Ikeda) infection at 4 months of age but no effect on calf susceptibility of dam infection status at calving. There was a significant negative effect of infection intensity on haematocrit after controlling for whether the infected animal was a dam or a 4 month old calf. Vertical trans-uterine transmission of T. orientalis (Ikeda) infection is unlikely in chronically infected dairy cows and thus not a factor in the epidemiology of T. orientalis (Ikeda) infection.
Publisher: BMJ
Date: 27-10-2020
Abstract: There are several previous studies on the association of vitamin E with prevention of stroke but the findings remain controversial. We have conducted a systematic review, meta-analysis together with trial sequential analysis of randomised controlled trials to evaluate the effect of vitamin E supplementation versus placebo/no vitamin E on the risk reduction of total, fatal, non-fatal, haemorrhagic and ischaemic stroke. Relevant studies were identified by searching online databases through Medline, PubMed and Cochrane Central Register of Controlled Trials. A total of 18 studies with 148 016 participants were included in the analysis. There was no significant difference in the prevention of total stroke (RR (relative risk)=0.98, 95% CI 0.92–1.04, p=0.57), fatal stroke (RR=0.96, 95% CI 0.77–1.20, p=0.73) and non-fatal stroke (RR=0.96, 95% CI 0.88–1.05, p=0.35). Subgroup analyses were performed under each category (total stroke, fatal stroke and non-fatal stroke) and included the following subgroups (types of prevention, source and dosage of vitamin E and vitamin E alone vs control). The findings in all subgroup analyses were statistically insignificant. In stroke subtypes analysis, vitamin E showed significant risk reduction in ischaemic stroke (RR=0.92, 95% CI 0.85–0.99, p=0.04) but not in haemorrhagic stroke (RR=1.17, 95% CI 0.98–1.39, p=0.08). However, the trial sequential analysis demonstrated that more studies were needed to control random errors. Limitations of this study include the following: trials design may not have provided sufficient power to detect a change in stroke outcomes, participants may have had different lifestyles or health issues, there were a limited number of studies available for subgroup analysis, studies were mostly done in developed countries, and the total s le size for all included studies was insufficient to obtain a meaningful result from meta-analysis. In conclusion, there is still a lack of statistically significant evidence of the effects of vitamin E on the risk reduction of stroke. Nevertheless, vitamin E may offer some benefits in the prevention of ischaemic stroke and additional well-designed randomised controlled trials are needed to arrive at a definitive finding. PROSPERO registration number: CRD42020167827.
Publisher: Informa UK Limited
Date: 11-08-2021
Publisher: Informa UK Limited
Date: 08-11-2017
DOI: 10.1080/00480169.2017.1391142
Abstract: To present the haematology and biochemistry profiles for cattle in New Zealand naturally infected with Theileria orientalis Ikeda type and investigate if the results differed between adult dairy cattle and calves aged <6 months. Haematology and biochemistry results were obtained from blood s les from cattle which tested positive for T. orientalis Ikeda type by PCR, that were submitted to veterinary laboratories in New Zealand between October 2012 and November 2014. Data sets for haematology and biochemistry results were prepared for adult dairy cattle (n=62 and 28, respectively) and calves aged <6 months (n=62 and 28, respectively), which were matched on the basis of in idual haematocrit (HCT). Results were compared between age groups when categorised by HCT. Selected variables were plotted against in idual HCT, and locally weighted scatterplot smoothing (Loess) curves were fitted to the data for adult dairy cattle and calves <6 months old. When categorised by HCT, the proportion of s les with HCT <0.15 L/L (severe anaemia) was greater for adult dairy cattle than for beef or dairy calves, for both haematology (p<0.002) and biochemistry (p<0.001) submissions. There were differences (p<0.05) between adult dairy cattle and calves aged <6 months in the relationships between HCT and red blood cell counts, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentrations, lymphocyte and eosinophil counts, and activities of glutamate dehydrogenase and aspartate aminotransferase. In both age groups anisocytosis was frequently recorded. The proportion of blood smears showing mild and moderate macrocytosis was greater in adults than calves (p=0.01), and mild and moderate poikilocytosis was greater in calves than adults (p=0.005). The haematology and biochemistry changes observed in cattle infected with T. orientalis Ikeda type were consistent with extravascular haemolytic anaemia. Adult dairy cattle were more likely to be severely anaemic than calves. There were differences in haematology and biochemistry profiles between adult dairy cattle and calves, but most of these differences likely had a physiological rather than pathological basis. Overall, the haematological changes in calves aged <6 months appeared less severe than in adult dairy cattle.
Publisher: MDPI AG
Date: 14-08-2020
DOI: 10.3390/ANI10081427
Abstract: Data on the scope of bacterial pathogens present and the frequency of antimicrobial resistance (AMR) in New Zealand’s pigs are limited. This study describes bacterial isolates, antimicrobial susceptibility data, and multidrug resistance (MDR resistance to ≥3 antimicrobial classes) from New Zealand pig submissions. Porcine test data from June 2003 to February 2016 were obtained from commercial veterinary pathology laboratory records. In total, 470/477 unique submissions resulted in bacterial growth, yielding 779 isolates. S le type was recorded for 360/477 (75.5%) lung (79/360 21.9%), faecal (61/360 16.9%) and intestinal (45/360 12.5%) were most common. The most common isolates were Escherichia coli (186/779, 23.9%), Actinobacillus pleuropneumoniae (43/779 5.5%), Streptococcus suis (43/779 5.5%), unidentified C ylobacter spp. (38/779 4.9%), alpha haemolytic Streptococci (32/779 4.1%), coagulase negative Staphylococcus spp. (26/779 3.3%), and Pasteurella multocida (25/779 3.2%). Susceptibility results were available for 141/779 (18.1%) isolates from 62/470 (13.2%) submissions. Most were susceptible to trimethoprim-sulphonamide (75/81 92.6%), but fewer were susceptible to penicillin (37/77 48.1%), tilmicosin (18/43 41.9%), or tetracyclines (41/114 36.0%). No susceptibility data were available for Salmonella spp., C ylobacter spp., or Yersinia spp. isolates. MDR was present in 60/141 (42.6%) isolates. More data on s le submission drivers, antimicrobial drug use, and susceptibilities of important porcine bacterial isolates are required to inform guidelines for prudent antimicrobial use, to reduce their prevalence, human transmission, and to minimise AMR and MDR.
Publisher: Informa UK Limited
Date: 23-10-2015
DOI: 10.1080/00480169.2015.1090894
Abstract: To describe the epidemiology of the epidemic of bovine anaemia associated with Theileria orientalis infection (TABA) in New Zealand between 30 August 2012 and 4 March 2014. Blood s les and associated data were obtained from cases of TABA. The case definition for TABA was met when piroplasms were present on blood smears and the haematocrit was ≤0.24 L/L. S les were analysed using quantitative PCR (qPCR) assays for the detection of T. orientalis Ikeda type. Only cases that were positive in the qPCR assays were included in the analysis. A case herd was defined as a herd that had ≥1 animal positive for T. orientalis Ikeda. Movement records for farms were accessed through the national animal identification and tracing scheme. The OR for cattle movements onto a case farm compared to a non-case farm was estimated using a generalised estimating equation model and the geodesic distance for movements onto case and non-case farms compared using Student's t-test. The kernel-smoothed risk of disease at the farm level was calculated using an extraction map and the clustering of diseased farms in time and space was measured using the spatial temporal inhomogeneous pair correlation function. In the first 18 months there were 496 case herds 392 (79%) were dairy and 104 (21%) beef herds. Of 882 in idual cases, 820 (93.0%) were positive for T. orientalis Ikeda in the qPCR assays. Case herds were initially clustered in the Northland, then the Waikato regions. The OR for a case farm compared to a non-case farm having ≥1 inward cattle movements was 2.03 (95% CI=1.52-2.71) and the distance moved was 26 (95% CI=20.8-31.3) km greater for case farms. The risk of disease was highest in a north, north-eastern to south, south-western belt across the Waikato region. The spatial-temporal analysis showed significant clustering of infected herds within 20-30 days and up to 15 km distant from a case farm. Theileria orientalis Ikeda type is likely to have been introduced into regions populated with naïve cattle by the movement of parasitaemic cattle from affected areas. Local spread through dispersed ticks then probably became more important for disease transmission between herds once the disease established in a new area. Dairy and beef farming in the North Island of New Zealand will be significantly changed in the coming years by the incursion of this new disease.
Publisher: Informa UK Limited
Date: 11-11-2023
DOI: 10.1080/00480169.2022.2135626
Abstract: To collect baseline data from New Zealand sheep farmers on techniques for docking and castrating lambs, their perceptions of the level of pain lambs experience following these procedures, and their opinions about the use of pain relief. From a voluntary cross-sectional survey of New Zealand sheep farmers, descriptive statistics were provided for quantitative study variables. Thematic analysis was performed on the free-text comments. Univariable logistic regression was used to assess factors associated with farmers indicating they would consider using a device allowing administration of pain relief simultaneously with castration and tail docking. There were 432 survey responses containing sufficiently complete data for analysis. Of the 340 in iduals (77.5%) always or sometimes performing castration of ram lambs, 242 (72.2%) used rubber rings for complete castration, 23 (6.9%) used the short scrotum method for cryptorchid castration, and 75 (22.4%) used a combination of both methods. Of the 423 in iduals (97.9%) who indicated that they always or sometimes performed tail docking, 245 (57.9%) used a hot iron only, 148 (35.0%) used a rubber ring only, 26 (5.8%) used both methods, 3 (0.7%) used a surgical knife, and 1 (0.2%) provided no response. Less than 2% of respondents always or sometimes used pain relief for these procedures. Of the 432 respondents, 139 (32.2%) and 180 (41.7%) strongly agreed that castration and tail docking do not cause sufficient pain to warrant using pain relief, respectively. Time and cost were identified as major barriers to providing pain relief. In the unadjusted logistic regression analyses, respondents who were female, had high levels of education, had been farming < 20 years, who believed lambs experienced high levels of pain following the procedures, and who believed pain lasted longer than 6 hours, were more likely to indicate willingness to use pain control devices. Our results suggest very few New Zealand sheep farmers currently provide lambs with pain relief following tail docking or castration. This is likely due to the perception that the procedures are not painful enough to warrant pain relief, and concern over time and cost. This highlights the need to educate farmers about lamb pain and distress following tail docking and castration, and its negative impact on animal welfare. Farmers also need pain relief techniques and tools that can be administered simultaneously with these procedures to save time and labour cost.
Publisher: Elsevier BV
Date: 07-2016
DOI: 10.1016/J.VETPAR.2016.05.018
Abstract: The tick-borne haemoparasite Theileria orientalis is the most important infectious cause of anaemia in New Zealand cattle. Since 2012 a previously unrecorded type, T. orientalis type 2 (Ikeda), has been associated with disease outbreaks of anaemia, lethargy, jaundice and deaths on over 1000 New Zealand cattle farms, with most of the affected farms found in the upper North Island. The aim of this study was to model the relative environmental suitability for T. orientalis transmission throughout New Zealand, to predict the proportion of cattle farms potentially suitable for active T. orientalis infection by region, island and the whole of New Zealand and to estimate the average relative environmental suitability per farm by region, island and the whole of New Zealand. The relative environmental suitability for T. orientalis transmission was estimated using the Maxent (maximum entropy) modelling program. The Maxent model predicted that 99% of North Island cattle farms (n=36,257), 64% South Island cattle farms (n=15,542) and 89% of New Zealand cattle farms overall (n=51,799) could potentially be suitable for T. orientalis transmission. The average relative environmental suitability of T. orientalis transmission at the farm level was 0.34 in the North Island, 0.02 in the South Island and 0.24 overall. The study showed that the potential spatial distribution of T. orientalis environmental suitability was much greater than presumed in the early part of the Theileria associated bovine anaemia (TABA) epidemic. Maximum entropy offers a computer efficient method of modelling the probability of habitat suitability for an arthropod vectored disease. This model could help estimate the boundaries of the endemically stable and endemically unstable areas for T. orientalis transmission within New Zealand and be of considerable value in informing practitioner and farmer biosecurity decisions in these respective areas.
Publisher: Informa UK Limited
Date: 20-12-2018
DOI: 10.1080/00480169.2018.1547227
Abstract: The principle aim of this study was to examine the association between infection with Theileria orientalis Ikeda type and growth rates of suckled beef calves on four beef farms. In addition, associations between calf sex, s ling time, and in idual farm and T. orientalis Ikeda type infection intensity and haematocrit (HCT) were investigated. The study was a prospective longitudinal study in which 240 calves from four purposively selected beef farms in the North Island of New Zealand were blood s led and weighed in late spring, mid-summer and early autumn. Two farms were from high-risk (A and B) and two from low-risk (C and D) tick areas. Blood s les were analysed to determine HCT, and the number of T. orientalis Ikeda type organisms/µL of blood (infection intensity) using a quantitative PCR assay. A calf was defined as infected if >415 organisms/µL were detected in a blood s le. Linear mixed models were used to examine associations between infection intensity, mean daily liveweight gain (MDG), HCT, calf sex and time of s ling on the four farms. On Farms A and B nearly all calves were infected at each s ling time, on Farm C <30% were infected at any s ling and on Farm D infection prevalence increased from 32 to 79% between late spring and early autumn. On Farms C and D, from mid-summer to early autumn, mean MDG was 0.127 (95% CI=0.072-0.183) kg/day less for infected than uninfected calves (p<0.001). On all farms MDG was negatively associated with infection intensity for mid-summer and early autumn s ling times (p=0.037). The relationship between time of s ling and infection intensity varied between farms (p<0.001), and between male and female calves (p=0.018). Females had a higher infection intensity than males at the mid-summer and early autumn s lings. The association between HCT and infection intensity varied with s ling time and farm (p=0.018). There was a strong negative association between infection intensity and HCT at the late spring s ling, but in mid-summer there was no association, and in early autumn only a weak association. This study has shown that beef farmers in the North Island of New Zealand should be concerned about the welfare effects and economic impacts of T. orientalis Ikeda type infection in suckled beef calves.
Publisher: Elsevier BV
Date: 06-2020
Publisher: Elsevier BV
Date: 09-2008
DOI: 10.1016/J.TVJL.2007.06.006
Abstract: Recent work has suggested that the recommended intakes of vitamin E for dairy cattle need to be increased, particularly in dry cows. However, these suggestions are based on data from cattle in the USA, which may have significantly different oxidative stresses than European cattle. This study, which involved 594 cattle on three dairy farms, was designed to determine the effect of increased vitamin E supplementation on the health and fertility of UK dairy cows. Cattle were randomly allocated to receive either two intramuscular injections of 2100 mg of vitamin E (and 7 g of sodium selenite) 2 weeks before calving and on the day of calving, or no additional vitamin E supplementation. Although supplementation had no effect on milk yield, reproductive efficiency, or incidence of uterine infections, supplemented cattle had a lower risk of culling and a lower rate of mastitis. These figures were economically significant but not statistically significant at the 10% level. Supplementation reduced the incidence of retained fetal membranes from 6.5% to 3%, an effect which was almost significant at the 5% level. If these data are representative they suggest that vitamin E recommendations for UK cattle should be reassessed.
Publisher: Informa UK Limited
Date: 05-03-2023
Publisher: Elsevier BV
Date: 10-2012
DOI: 10.1016/J.VETPAR.2012.05.003
Abstract: A randomised clinical trial from the North Island of New Zealand was conducted to assess the effect of repeated anthelmintic treatment on milk production, and to assess factors that affect treatment response. Nine hundred and twenty three multiparous, lactating dairy cattle from three pasture-based, spring-calving dairy herds were enrolled in this trial. Within each herd, cattle were stratified on age and calving date, and were randomly allocated to treatment (n=319) or control (n=604) groups. The treatment group received ≥ 0.05 mg/kg of topical eprinomectin every 28 days for eight treatments during lactation. Pooled-milk from treated cows and bulk-milk s les were obtained at each treatment and analysed with an Ostertagia antibody ELISA, expressed as optical density ratios (ODR). Bi-monthly milk data were collected and expressed as energy-corrected milk (kg/day ECM). A linear mixed model was used to analyse ECM, with cow as the random effect. The effect of anthelmintic treatment on days from calving, and start-of-mating, to conception were analysed with Cox-proportional hazard models. ODR values ranged from 0.6 to 1.3 there were no differences in ODR between herds (p=0.12), or between pooled-milk from treated cows and bulk-milk (p=0.26). Repeated treatments had no effect on daily ECM yields (p=0.74). However, there was a significant treatment × herd interaction (p=0.03) treatment increased ECM in one herd by 0.781 kg/cow/day (p=0.015), but resulted in a non-significant decrease in the other two herds. A curvilinear interaction existed between days-in-milk and treatment response (p=0.039) the greatest treatment effect occurred during mid-lactation. Previous year milk production (p=0.46) and age (p=0.11) did not influence the effect of treatment on ECM. Treatment had no effect on any reproductive parameter. In conclusion, under New Zealand pastoral conditions, anthelmintic treatment increased milk production in one herd, but had no effect in two other herds. Further work is needed to identify why this variation in gastro-intestinal parasitism occurs.
Publisher: Springer Science and Business Media LLC
Date: 21-01-2020
DOI: 10.1007/S10493-019-00460-7
Abstract: Although currently exotic to New Zealand, the potential geographic distribution of Amblyomma americanum (L.), the lone star tick, was modelled using maximum entropy (MaxEnt). The MaxEnt model was calibrated across the native range of A. americanum in North America using present-day climatic conditions and occurrence data from museum collections. The resulting model was then projected onto New Zealand using both present-day and future climates modelled under two greenhouse gas emission scenarios, representative concentration pathways (RCP) 4.5 (low) and RCP 8.5 (high). Three sets of WorldClim bioclimatic variables were chosen using the jackknife method and tested in MaxEnt using different combinations of model feature class functions and regularization multiplier values. The preferred model was selected based on partial receiver operating characteristic tests, the omission rate and the lowest Akaike information criterion. The final model had four bioclimatic variables, Annual Mean Temperature (BIO 1 ), Annual Precipitation (BIO 12 ), Precipitation Seasonality (BIO 15 ) and Precipitation of Driest Quarter (BIO 17 ), and the projected New Zealand distribution was broadly similar to that of Haemaphysalis longicornis Neumann, New Zealand’s only livestock tick, but with a more extensive predicted suitability. The climate change predictions for the year 2050 under both low and high RCP scenarios projected only moderate increases in habitat suitability along the mountain valleys in the South Island. In conclusion, this analysis shows that given the opportunity and license A. americanum could and would successfully establish in New Zealand and could provide another vector for theileriosis organisms.
Publisher: Springer Science and Business Media LLC
Date: 24-01-2019
DOI: 10.1038/S41598-018-37205-2
Abstract: The North American distributional potential of the recently invaded tick, Haemaphysalis longicornis , was estimated using occurrence data from its geographic range in other parts of the world and relevant climatic data sets. Several hundred candidate models were built using a correlative maximum entropy approach, and best-fitting models were selected based on statistical significance, predictive ability, and complexity. The median of the best-fitting models indicates a broad potential distribution for this species, but restricted to three sectors—the southeastern United States, the Pacific Northwest, and central and southern Mexico.
Publisher: Informa UK Limited
Date: 06-05-2019
Publisher: Elsevier BV
Date: 08-2017
DOI: 10.1016/J.VETPAR.2017.07.001
Abstract: Haemaphysalis longicornis is the only species of tick present in New Zealand which infests livestock and is also the only competent vector for Theileria orientalis. Since 2012, New Zealand has suffered from an epidemic of infectious bovine anaemia associated with T. orientalis, an obligate intracellular protozoan parasite of cattle and buffaloes. The aim of this study was to predict the spatial distribution of habitat suitability of New Zealand for the tick H. longicornis using a simple rule-based climate envelope model, to validate the model against published data and use the validated model to project an expansion in habitat suitability for H. longicornis under two alternative climate change scenarios for the periods 2046-2065 and 2081-2100, relative to the climate of 1981-2010. A rule-based climate envelope model was developed based on the environmental requirements for off-host tick survival. The resulting model was validated against a maximum entropy environmental niche model of environmental suitability for T. orientalis transmission and against a H. longicornis occurrence map. Validation was completed using the I-similarity statistic and by linear regression. The H. longicornis climate envelope model predicted that 75% of cattle farms in the North Island, 3% of cattle farms in the South Island and 54% of cattle farms in New Zealand overall have habitats potentially suitable for the establishment of H. longicornis. The validation methods showed an acceptable level of agreement between the envelope model and published data. Both of the climate change scenarios, for each of the time periods, projected only slight to moderate increases in the average farm habitat suitability scores for all the South Island regions. However, only for the West Coast, Marlborough, Tasman, and Nelson regions did these increases in environmental suitability translate into an increased proportion of cattle farms with low or high H. longicornis habitat suitability. These results will have important implications for the geographical progression of Theileria-associated bovine anaemia (TABA) in New Zealand and will also be of interest to Haemaphysalis longicornis researchers in Australia, Japan, Korea and New Zealand.
Publisher: Elsevier BV
Date: 09-2016
DOI: 10.1016/J.VETPAR.2016.05.033
Abstract: Infections of ruminants with Fasciola hepatica are considered to be of regional importance within New Zealand but there is very little recent information on its prevalence or severity other than anecdotal reports. Generally they are considered to be of secondary importance compared to gastrointestinal nematode infections. Utilizing data from Virtual Climate Stations (n=11491) distributed on a 5km grid around New Zealand a growing degree-day model was used to describe the risk of infection with liver fluke from 1972 to 2012 and then to apply the predictions to estimate the risk of fluke infections within New Zealand for the years 2040 and 2090. The growing degree-day model was validated against the most recent survey of infection within New Zealand in 1984. A strong positive linear relationship for 1984 between F. hepatica prevalence in lambs and infection risk (p<0.001 R
Publisher: Informa UK Limited
Date: 21-08-2017
DOI: 10.1080/00480169.2017.1364180
Abstract: AIM To determine the most commonly used words in the clinical histories of animals naturally infected with Theileria orientalis Ikeda type whether these words differed between cases categorised by age, farm type or haematocrit (HCT), and if there was any clustering of the common words in relation to these categories. METHODS Clinical histories were transcribed for 605 cases of bovine anaemia associated with T. orientalis (TABA), that were submitted to laboratories with blood s les which tested positive for T. orientalis Ikeda type infection by PCR analysis, between October 2012 and November 2014. χ
Location: United Kingdom of Great Britain and Northern Ireland
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Kevin Lawrence.